Acrylamide/2-acryloxyethyltrimethylammonium chloride copolymers in inverse microemulsions, with 60% 2-acryloxyethyltrimethyl ammonium chloride in the monomer feed and a concentration of active matter of 30% (w/w) as flocculants, were obtained by inverse micro-emulsion copolymerization. Inverse microemulsion formulations of comonomers, interesting from both technical and economical viewpoints, were polymerized by semicontinuous free-radical copolymerization with sodium disulfite as the initiator. The influence of the formulation composition, hydrophilic-lipophilic balance (HLB), starting polymerization temperature, and reaction time on the polymerization and final properties of the products as flocculants was studied. (C) 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 186-197, 2007